The eye is an extremely precise and delicate instrument, and even the slightest defect in its shape can cause distortions in vision. These tiny imperfections in the curve of the cornea, called refractive errors, are by far the most common cause of minor to moderate visual impairment worldwide. In fact, according to the American Academy of Ophthalmology, more than 150 million Americans use corrective eyewear, such as eyeglasses or contact lenses, to compensate for refractive errors in vision, at a cost of more than $15 billion each year. Fortunately there are many different treatment options designed to address this extremely common array of problems.
The eye works by using a tiny lens at the front of the eye to focus light from the outside world onto the light sensitive retina at the back of the eye, not unlike the way a movie projector focuses images on a movie screen. The sensitive photoreceptors that line the retina translate this stimulus into nerve impulses that are then sent to the brain for interpretation. However, when the shape of the cornea is distorted in any way, the light from the lens does not focus clearly, causing the image to become blurred. For example, if the eye is elongated, shaped more like a football than a basketball, then the light comes to a focused point before it reaches the retina, resulting in myopia or nearsightedness. Similarly, an eyeball that is too short can result in hyperopia or farsightedness while one that is irregularly shaped can cause the visual distortions common to astigmatism. The shape of the eye itself is not the only factor that can result in refractive errors, however. As the eye gets older the muscles that control the focus of the eye can slowly lose their strength and elasticity. Eventually this can result in presbyopia, where the eye muscles lose the ability to bend the lens to the degree necessary to focus on close objects.
Refractive errors are most commonly corrected with eyeglasses or contact lenses. The addition of a second artificial lens in front of the eye is usually sufficient to bring images into clear focus. However, many patients, particularly those in fast-moving, physically demanding careers or those tired of the ongoing expense and inconvenience of contact lenses, may prefer to have their refractive errors corrected with laser eye surgery. LASIK, short for laser-assisted in-situ keratomileusis, is a common type of refractive eye surgery that uses an excimer laser to vaporize and remove the previously determined thickness of excess corneal tissue, effectively reshaping the curve of the eyeball into a more efficient shape. LASIK surgery can reduce or even eliminate an individual’s need for corrective lenses with virtually no surgical downtime.
If you have questions about refractive errors, or would like to schedule an appointment for an eye exam, please contact Georgia Eye Physicians and Surgeons today to make an appointment. Be sure to follow us on Facebook, Twitter, and Google+ for more tips for healthy eyes.